The present invention relates broadly to internal combustion engines and, more particularly, to an improved internal combustion engine having a rotary valve with improved seals.
Rotary valve engines are known generally as variations, with respect to the transfer of gases, on more conventional internal combustion engines. Rotary valve engines typically use a rotating ported cylinder in place of standard poppet valves in the cylinder head. Basically, the cylinder is caused to rotate due to some mechanical linkage with the crank shaft of the engine. The placement of the ports and channels through the cylindrical valve member are caused to go into and out of registry with openings in the cylinder head to feed the fuel/air mixture into the cylinder or to remove exhaust gases therefrom. As may be expected, timing is an important aspect of rotary valve design.
Rotary valve engines, when properly constructed, provide advantages over conventional engines using poppet valves. Initially, the valve train is much simpler in that there are fewer moving parts. Further, since the rotary valve engine is nonreciprocating, impulse forces on the valves and valve components are not present because there is no change of direction in valve movement. Accordingly, rotary valve engines are typically smoother in operation than poppet valve engines. Additionally, the rotary valve engine offers an open port to the combustion chamber instead of a port partially blocked by poppet valve. In addition, the compression ratio of any given engine can be raised by increasing piston excursion distance because there is no poppet valve projecting into the combustion chamber that the piston must avoid along its reciprocatory path within the cylinder. Rotary valve engines provide enhanced high RPM performance because the rotary valve engine does not rely on valve springs to close a valve which, at high RPM, can lag behind the piston. This is especially true in the case of weak or worn valve springs.
Rotary valve engines, in general are well known in the art and have been for quite some time. Examples of rotary valve engine patents include Fountain & Langford, U.S. Pat. No. 1,191,684, Lockshaw U.S. Pat. No. 4,016,840 and Guenther U.S. Pat. No. 4,036,184. Even with these varied and unique approaches, a problem with rotary valve engines, a problem shared with many rotary components, is that of sealing. Rotary valve engines tend to leak if the tolerances are loose enough to permit free rotation, yet closer tolerances tend to make the engine seize.
An approach to the sealing problem is found in the Vallejos U.S. Pat. No. 4,119,077 which applies a complex mechanism to one of the sealing problems. Sealing problems can occur between cylinders along the rotary valve members. Separate, but no less problematic, sealing problems can occur between the combustion chamber and the valve member itself when the ports in the valve member have rotated out of registry with the port in the cylinder head leading to the combustion chamber. However effective the Vallejos 077 sealing apparatus is, Vallejos 077 provides a complex mechanism to achieve the necessary sealing.